AAT/H claims and the facts:

Below are some key AAT/H claims
juxtaposed with the relevant, and contrary, facts.
Most also have either
references or links to more information on these facts or in-depth examinations
of the claims (more will be added as I complete them):

Claim: Human hairlessness is explained by an aquatic past

Fact: Humans' relative
hairlessness
is unlike aquatic mammals, because A) most aquatic mammals aren't hairless;
and B) those few that are have skin that's radically different from
humans (there's a link for this in the seal skin and sweat section below).

Claim: The pattern of
human hair alignment is strikingly different from apes and indicates streamlining
for swimming.

Fact: The pattern of
human hair alignment is only very slightly different from apes.
Also, in order for this pattern to indicate streamlining for swimming we would have
to be swimming with the crown of the head facing straight forward and your
arms held at your sides.
Just take a look.
This is so easy
to see, you've got to wonder how AAT/H proponents can make the claim, or why it's
swallowed so uncritically.
There's also the problem that humans are
not even close to being fast swimmers to whom streamlining therefore might
help (more info in the "hairlessness" link above).

Claim: The human body
responds the same to the act of standing up as it does to surgery or massive
haemorrhage but this reaction doesn't occur when standing up in water.

Fact:
Ooh, this
is a thorny thicket; neither part is true but are misrepresentations of
facts twisted about to make a point which isn't true sound true.
To see how and why, you'll have to read this link on aldosterone
and bipedalism.

Fact: Humans are the
only mammals proven to cry emotional tears.
There are no animals other than humans which have been scientifically proven
as having emotional tears.
However, there are unproved accounts of many
other mammals crying emotional tears, but these are not just aquatic animals;
they include dogs and wolves, seal, sea otter, lab rats, cats, cows, pigs,
lambs, horse, a kangaroo and a gorilla.

Claim: Only marine reptiles
and birds have salt glands.

Fact:
Salt
glands are found in many non-marine reptiles and birds, including ostriches
and other birds, and many lizards, including iguanas, chuckwallas, and
others.

Claim: The human response
to salt indicates we evolved in a salt-water environment.

Fact: Human responses
to salt are similar to terrestrial mammals, including chimps.
Mammals which live in salt-rich environments do not exhibit these responses as
humans do.
Our salt mechanisms indicate a terrestrial past with a large
herbivorous component to our diet, unlike the AAT/H claims.

Fact: Non-human, non-aquatic
animals can and do hold their breath (refs in diving reflex link above).

Claim: The descended
larynx of humans is like that of aquatic mammals, and must have arisen
in an aquatic environment.
Although it's necessary to make all the complex
sounds we use in speech, it cannot have arisen for that purpose, because
it wouldn't be useful for that purpose in its initial stages.

Fact: The descended
larynx of humans is not particularly similar to those which are found in
(only a very few) aquatic mammals (refs and info in diving reflex link
above).
Previously here I'd said that the evidence from the fossil record also indicates that this
feature developed several million years after the purported aquatic period, but research on the larynx over the past shows this is actually a far more common trait than previously thought, and is primarily because of vocalization (see the "descended larynx" section of the breathholding, descended larynx, and diving reflex link).

Claim: Non-human primates
have nostrils that point forward, unlike humans.

Fact: What can I say;
Old World primates are in fact called Catarrhine primates precisely
because their nostrils face down.
Morgan likes to try to have this
one both ways; while she claims that forward-facing nostrils are detrimental
to aquaticism, and that we had a human-like nose several million years
before the bones on our ancestors' faces indicate they did, she takes the
nose of both male proboscis monkeys (with its downward-facing nostrils)
and
of female and juvenile proboscis monkeys (which face as much forward as other Old World monkeys) as aquatic
adaptations.
(Scientists who study these monkeys' behavior
say it's sexual selection, as is true of all sexually dimorphic traits
which aren't due to differences in use.)
She even has a drawing of
a juvenile proboscis monkey swimming in her latest book which, according
to her theory, should have water shoved up his forward-facing nostrils.
Why, if it's no problem for a monkey, would it be such a big problem for
hominids as to force a massive change?
Morgan doesn't see the contradiction.

Claim: Our ancestors
wouldn't have changed from quadrupedalism to bipedalism, because initially
bipedalism would be less efficient than quadrupedalism.

Fact: Actual tests of
chimpanzees by Taylor and Rowntree in 1973 (Science 176: 186-187)
has shown that bipedalism is no less efficient for them than quadrupedalism.
It wouldn't be for our ancestors, even if they evolved from knuckle-walking
apes such as chimps.
Also, the consensus over the last few decades
has been that the LCA was far more likely to have been a brachiating (swinging
from branches) ape rather than a knuckle-walker, which makes it even less
of a problem to be bipedal.
In fact, brachiating apes -- such as
gibbons -- virtually always walk bipedally when they are on the
ground.

Claim: Proboscis monkeys
use bipedalism more often than other primates and often walk bipedally
as "merely an alternative locomotor mode of getting from A to B."

Fact: Morgan bases this
claim on several seconds of film taken by Japanese filmmakers, which showed
several proboscis monkeys walking bipedally.
On this subject,
I just (August 9, '01) watched a TV program, "The Secret World of the Proboscis
Monkeys", and over the course of the hour, those obnoxious primates simply
refused to do any bipedal walking.
Perhaps it was because it was
French filmmakers this time, or maybe the anthropological conspiracy quashed
all the bipedal episodes.
Or, just possibly, it's what years of observations
by primatologists tell us:
Proboscis monkeys don't walk bipedally
more often than other primates (all primates use bipedalism occasionally).

Claim: It was too dangerous
for our ancestors to live on land during the transition from ape ancestor
to hominid.
The water provided safety from predators.

Fact: The water environment
would be far more dangerous than the land environment; the predators
there are more numerous and harder to deal with.

Claim: Our ancestors
couldn't have dealt with predators on land, because the only way to do
so is to run away, and we weren't fast enough and there were no trees to
climb.

Fact: Not only were
there trees in the hominids' environment (see savannah
definition if you haven't already), but it is unlikely we would have
been limited to running from predators.
How we probably would have handled
them is how chimpanzees handle predators now (see the predators link just
above).

Claim: The body temperature
of normal, healthy humans is the same as that of whales, rather than our
primate relatives or other terrestrial mammals, and it doesn't fluctuate,
while that of terrestrial mammals does.

Fact: The body
temperature of normal, healthy humans is like that of our primate relatives,
it does normally fluctuate, and it's not like that of whales.

Claim: Hymens are an
aquatic trait.

Fact: Besides humans,
hymens are found in lemurs (fellow primates, you'll note), guinea pigs,
mole rats, hyenas, horses, llamas, elephants, rats, horses, and some species of galago, as well as in aquatic mammals such as toothed whales, seals, and sirenia.
Among these, toothed whales, seals, and sirenia are aquatic.
And note that the aquatic ones are fully aquatic, not casual dip in the water types; once again AAT/H proponents are comparing us to mammals which have been fully aquatic for tens of millions of years.

There's another thing: the hymen seems to vary an awful lot, so much that it doesn't look like you can make the easy comparisons across species the AAT/H relies on.
For instance, guinea pigs' hymens are quite different from most others, and those in whales are apparently different enough that various textbooks refer to them as "vaginal bands" or refer to "a hymen-equivalent possibly present in juveniles" ("Reproduction in
Marine Mammals" by Ian L. Boyd, Christina Lockyer, and Helene D. Marsh, in Biology of marine mammals edited by John E. Reynolds III and Sentiel A. Rommel, 1999).

Also, AAT/H proponents suggest that the reason
for a hymen in humans was to seal off the female reproductive organs from
waterborne parasites and such; but since the hymen is generally absent
from the time of first intercourse (and very often before) this protection
wouldn't be available for much of the female's lifespan.

Claim: Vibrissae (sensory
whiskers) are absent only in humans and in aquatic mammals.

Fact:
Among aquatic
mammals, vibrissae are actually absent only in some types of whales (whales
such as blue, fin, and humpback whales have them) and of course they are
abundant and very sensitive in most aquatic mammals.
They are, however,
also absent in other, terrestrial, mammals, such as tree shrews and the
monotremes (platypus and echidna).
The great apes have few vibrissae
compared to other mammals, and their absence in humans seems to be yet
another of the "continuation of a trend" features we see in primates (hair
and sweat glands are other such features).
A few minutes search on
the web (using the term "vibrissae" with either "primates", "comparative",
or "whales") easily turned up this information.
Why do AAT/H proponents not do even so easy and basic research as this before making their claims?

Claim: Human fat quantity
and distribution is like that of aquatic mammals; it is adapted for insulation
and swimming in an aquatic environment.
Humans have subcutaneous
fat which is bonded to the skin rather than anchored within the body, unlike
non-aquatic mammals.

Fact: Human fat
characteristics show no sign of any aquatic adaptation, and are radically
different from the aquatic mammals AAT/H proponents say we resemble.
Human fat deposits are anchored to underlying depots, just as those of all mammals
are.
Human fat deposits are found in the same places, and are anchored the
same way, as those of other primates.

Claim: Human sebaceous
glands waterproof the skin, like the sebaceous glands of seals (and that
"Sebum is an oily fluid whose only known function in mammals is waterproofing
the hair and skin.").

Fact: Sebaceous glands
cannot waterproof human skin (which is why your skin wrinkles when wet).
This is because human skin is very different than the skin
of seals.
And that's not the only evidence that human sebaceous
glands are not an aquatic adaptation.
The primary function of sebum,
the output of the sebaceous glands, is to produce scent (generally as
a sexual attractor).
This is true of a variety of mammals, including
humans.
In some seals, sebum can also keep their highly specialized
skin pliable as an aid in waterproofing (refs in "skin" link).